Core C, the Mouse Breeding and Microsurgery and Procedure Core will serve all three Projects over all five years of the Program. There are two major functions of Core C: (1) The Mouse Breeding function will provide transgenic and null mice bred into specific genetic backgrounds to each of the three projects of the Program. This component will provide services to mate and genotype the animals required for Projects 1-2-3. (2) The Mouse Microsurgery and Procedure function will standardize microsurgery procedures and procedures carried out by the Projects, including the aorta transplant surgery (Project 1), fat transplantation (Projects 2&3), bone marrow transplantation (Project 1) and glucose and insulin tolerance tests (Projects 1,2,&3).